Indigenous plants generally require no special attention. By definition they are plants which are native to the area and are suited for the environment in which they live. However, many gardeners desire to landscape with non-native plants because of their appearance or the fruit that they bear or the attractive flowers or blossoms that they produce. Despite attempts to climatize these desired plants through hybridization, many plants still have a limited tolerance for extreme temperatures and excessively dry or moist conditions. Thus, many of these non-native plants need an environment in which these factors can be controlled.
Non-native plants and other exotic plants can be grown in traditional greenhouses. However, greenhouses are relatively expensive to buy and occupy a large space in the yard. In addition, greenhouses require construction and assembly. More significantly to the gardener, if the plants are chosen for their decorative effect, for instance azaleas and gardenias, then growing them in greenhouses would defeat this purpose.
U.S. Pat. No. 2,835,078 discloses a protective cover for perishable crops which includes a canopy of flexible, light transparent, moisture-proof material. The canopy is formed by stacking generally cylindrical members having progressively smaller upper and lower diameters one above the other and closing an upper opening with a cover.
U.S. Pat. No. 3,206,892 discloses several embodiments of a collapsible cold frame incorporating a collapsible transparent ballast tube filled with water and air to permit the passage of incident solar infrared radiations, so that the ground under the ballast tube becomes heated by the rays of the sun, and the water also traps long wave infrared heat radiations which tend to pass out of the earth during the colder portions of the day and the night, thereby maintaining a more even temperature for the earth under the ballast tube and within the cold frame. In one embodiment of the cold frame, a removable covering member is supported by collapsible curved, arcuate or V-shaped ribs secured to spaced ballast tubes.
U.S. Pat. No. 3,939,607 discloses a collapsible terrarium assembly which is inflatable to assume a desired configuration for transparently housing a potted plant. The structure includes a disk-like base and a dome formed by an open, flexible plastic envelope whose rim is secured to a coupling ring which is joinable to the base to form a hermetically-sealed enclosure which can be inflated through a valve.
U.S. Pat. No. 4,304,068 discloses a collapsible terrarium that includes a flexible fluid-impermeable enclosure which has a bottom portion and a top portion that includes a collapsible support structure resembling that of an umbrella frame.
Other protective covers for plants are disclosed in U.S. Pat. No. 4,347,685 and U.S. Pat. No. 4,290,242.
Collapsible covers for plants heretofore devised do not provide sufficient thermal insulating capability in a free-standing structure which can be quickly and easily erected for temporarily protecting tender plants.
Accordingly there is a need for a portable greenhouse that is easy to install, occupies minimal space, and is relatively inexpensive.